Zimo Liu

dblp:211/7223 · DBLP profile ↗
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17ranked-venue papers
4as first author
13since 2021 · last 2026
—ORCID · conflict

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Graphics, computer vision, multimedia, augmented reality and games · 14 · 3 first-author · 11 since 2021Artificial intelligence and machine learning · 12 · 3 first-author · 8 since 2021
YearPublicationVenuePosition
2026 DMGINE: Day-Memory Guided Nighttime Image Enhancement for Dynamic Traffic Scenes
abstract
We introduce Daytime-Memory Guided Nighttime Image Enhancement (DMGNIE) framework, the first framework that turns long-running daytime surveillance videos of a single intersection into persistent “daytime memory” to guide nighttime image enhancement in traffic scenes. Our key insight is simple yet powerful: for a static scene, perfectly exposed daytime frames are, pixel-for-pixel, high-quality illumination prior for the same location under extreme low-light. Due to the complex lighting conditions in real-world traffic scenes, existing low-light image enhancement (LLIE) methods suffer from issues such as overexposure in highlight regions and noise amplification in low-light condition regions, which degrades the performance of downstream computer vision tasks. DMGNIE tackles these issues in two steps: (1) SegBMN, a semantic prior-based background modeling network, distills a clean, static daytime background from hours of video as scene prior guiding the enhancement of nighttime image; (2) a Foreground Localization-Guided Contrastive Learning module avoid the interference from the background prior with foreground objects during the guidance by maximizing the differences between foreground and background features. Finally, We conduct comprehensive experiments on real traffic surveillance datasets of two cities to evaluate the effectiveness. And the experimental results demonstrate that DMGNIE outperforms state-of-the-art baselines and achieves superior performance in challenging low-light conditions.
Ruizhou Liu, Zhe Wu 0006, Zimo Liu, Qingming Huang
AAAI3
2026 Discrepancy-Controlled Region-Adaptive Learning: Handling Intra-Domain Bias for Crowd Counting
abstract
Crowd counting in congested scenarios remains challenging, when required to handle“intra-domain bias”—the significant variation in crowd density across regions within each image. In this study, we propose a novel Discrepancy-Controlled Region-Adaptive Learning (DC-RA) method which leverages a divide-and-conquer strategy, transforming the complex problem of image-level crowd counting into a series of more manageable regional tasks. Specifically, we propose a Discrepancy-Controlled Adaptive Partition (DCAP) module, to divide each image to regions that adapt to the varying density levels controlled by discrepancy of crowd density. To specify features for each region, the Region-wise Adaptive Learning (RAL) module is then introduced by incorporating the Mixture-of-Experts (MoE) framework, which involves using a routing module to select the most suitable expert for each region. This dynamic selection process ensures that each region benefits from tailored optimization based on its specific characteristics, leading to more precise density estimates. To ensure that each expert captures the distinct characteristics of various regions, we further incorporate a region-level counting loss for optimization. Experiments show that DC-RA reduces the Mean Absolute Errors (MAE) by 2.5 and 4.1 compared with the state-of-the-art method on JHU-CROWD++ and NWPU, respectively, significantly enhancing the model’s robustness and accuracy across varying crowd densities.
Mingyue Guo 0001, Zimo Liu, Yaowei Wang 0001, Qixiang Ye
IEEE Trans. Circuits Syst. Video Technol.2
2025 DM-Adapter: Domain-Aware Mixture-of-Adapters for Text-Based Person Retrieval
abstract
Text-based person retrieval (TPR) has gained significant attention as a fine-grained and challenging task that closely aligns with practical applications. Tailoring CLIP to person domain is now a emerging research topic due to the abundant knowledge of vision-language pretraining, but challenges still remain during fine-tuning: (i) Previous full-model fine-tuning in TPR is computationally expensive and prone to overfitting.(ii) Existing parameter-efficient transfer learning (PETL) for TPR lacks of fine-grained feature extraction. To address these issues, we propose Domain-Aware Mixture-of-Adapters (DM-Adapter), which unifies Mixture-of-Experts (MOE) and PETL to enhance fine-grained feature representations while maintaining efficiency. Specifically, Sparse Mixture-of-Adapters is designed in parallel to MLP layers in both vision and language branches, where different experts specialize in distinct aspects of person knowledge to handle features more finely. To promote the router to exploit domain information effectively and alleviate the routing imbalance, Domain-Aware Router is then developed by building a novel gating function and injecting learnable domain-aware prompts. Extensive experiments show that our DM-Adapter achieves state-of-the-art performance, outperforming previous methods by a significant margin.
Zimo Liu, Xiangyuan Lan, Wenming Yang, Yaowei Li 0001, Qingmin Liao
AAAI2
2025 Pre-Trained Vision-Language Models as Noisy Partial Annotators
abstract
In noisy partial label learning, each training sample is associated with a set of candidate labels, and the ground-truth label may be contained within this set. With the emergence of powerful pre-trained vision-language models, e.g. CLIP, it is natural to consider using these models to automatically label training samples instead of relying on laborious manual annotation. In this paper, we investigate the pipeline of learning with CLIP annotated noisy partial labels and propose a novel collaborative consistency regularization method, in which we simultaneously train two neural networks, which collaboratively purify training labels for each other, called Co-Pseudo-Labeling, and perform consistency regularization between label and representation levels. For instance-dependent noise that embodies the underlying patterns of the pre-trained model, our method employs multiple mechanisms to avoid overfitting to noisy annotations, effectively mines information from potentially noisy sample set while iteratively optimizing both representations and pseudo-labels during the training process. Comparison experiments with various kinds of annotations and weakly supervised methods, as well as other pre-trained model application methods demonstrates the effectiveness of method and the feasibility of incorporating weakly supervised learning into the distillation of pre-trained models.
Qian-Wei Wang, Yuqiu Xie, Zimo Liu, Shutao Xia
AAAI4
2025 Morph: a Motion-Free Physics Optimization Framework for Human Motion Generation
abstract
Human motion generation has been widely studied due to its crucial role in areas such as digital humans and humanoid robot control. However, many current motion generation approaches disregard physics constraints, frequently resulting in physically implausible motions with pronounced artifacts such as floating and foot sliding. Meanwhile, training an effective motion physics optimizer with noisy motion data remains largely unexplored. In this paper, we propose \textbf{Morph}, a \textbf{Mo}tion-F\textbf{r}ee \textbf{ph}ysics optimization framework, consisting of a Motion Generator and a Motion Physics Refinement module, for enhancing physical plausibility without relying on expensive real-world motion data. Specifically, the motion generator is responsible for providing large-scale synthetic, noisy motion data, while the motion physics refinement module utilizes these synthetic data to learn a motion imitator within a physics simulator, enforcing physical constraints to project the noisy motions into a physically-plausible space. Additionally, we introduce a prior reward module to enhance the stability of the physics optimization process and generate smoother and more stable motions. These physically refined motions are then used to fine-tune the motion generator, further enhancing its capability. This collaborative training paradigm enables mutual enhancement between the motion generator and the motion physics refinement module, significantly improving practicality and robustness in real-world applications. Experiments on both text-to-motion and music-to-dance generation tasks demonstrate that our framework achieves state-of-the-art motion quality while improving physical plausibility drastically. Project page: https://interestingzhuo.github.io/Morph-Page/.
Mingshuang Luo, Ruibing Hou, Zimo Liu
ICCV7
2025 An Exploration with Entropy Constrained 3D Gaussians for 2D Video Compression
abstract
3D Gaussian Splatting (3DGS) has witnessed its rapid development in novel view synthesis, which attains high quality reconstruction and real-time rendering. At the same time, there is still a gap before implicit neural representation (INR) can become a practical compressor due to the lack of stream decoding and real-time frame reconstruction on consumer-grade hardware. It remains a question whether the fast rendering and partial parameter decoding characteristics of 3DGS are applicable to video compression. To address these challenges, we propose a Toast-like Sliding Window (TSW) orthographic projection for converting any 3D Gaussian model into a video representation model. This method efficiently represents video by leveraging temporal redundancy through a sliding window approach. Additionally, the converted model is inherently stream-decodable and offers a higher rendering frame rate compared to INR methods. Building on TSW, we introduce an end-to-end trainable video compression method, GSVC, which employs deformable Gaussian representation and optical flow guidance to capture dynamic content in videos. Experimental results demonstrate that our method effectively transforms a 3D Gaussian model into a practical video compressor. GSVC further achieves better rate-distortion performance than NeRV on the UVG dataset, while achieving higher frame reconstruction speed (+30%~40% fps) and stream decoding. Code is available at [Github](https://github.com/actcwlf/GSVC)
Bin Chen 0011, Zimo Liu, Yaowei Wang 0001, Shutao Xia
ICLR3
2025 UP-Person: Unified Parameter-Efficient Transfer Learning for Text-Based Person Retrieval
abstract
Text-based Person Retrieval (TPR) as a multi-modal task, which aims to retrieve the target person from a pool of candidate images given a text description, has recently garnered considerable attention due to the progress of contrastive visual-language pre-trained model. Prior works leverage pre-trained CLIP to extract person visual and textual features and fully fine-tune the entire network, which have shown notable performance improvements compared to uni-modal pre-training models. However, full-tuning a large model is prone to overfitting and hinders the generalization ability. In this paper, we propose a novelUnifiedParameter-Efficient Transfer Learning (PETL) method for Text-basedPersonRetrieval (UP-Person) to thoroughly transfer the multi-modal knowledge from CLIP. Specifically, UP-Person simultaneously integrates three lightweight PETL components including Prefix, LoRA and Adapter, where Prefix and LoRA are devised together to mine local information with task-specific information prompts, and Adapter is designed to adjust global feature representations. Additionally, two vanilla submodules are optimized to adapt to the unified architecture of TPR. For one thing, S-Prefix is proposed to boost attention of prefix and enhance the gradient propagation of prefix tokens, which improves the flexibility and performance of the vanilla prefix. For another thing, L-Adapter is designed in parallel with layer normalization to adjust the overall distribution, which can resolve conflicts caused by overlap and interaction among multiple submodules. Extensive experimental results demonstrate that our UP-Person achieves state-of-the-art results across various person retrieval datasets, including CUHK-PEDES, ICFG-PEDES and RSTPReid while merely fine-tuning 4.7% parameters. Code is available at https://github.com/Liu-Yating/UP-Person.
Yaowei Li 0001, Xiangyuan Lan, Wenming Yang, Zimo Liu, Qingmin Liao
IEEE Trans. Circuits Syst. Video Technol.5
2025 An Efficient Implicit Neural Representation Image Codec Based on Mixed Autoregressive Model for Low-Complexity Decoding
abstract
Displaying high-quality images on edge devices, such as augmented reality devices, is essential for enhancing the user experience. However, these devices often face power consumption and computing resource limitations, making it challenging to apply many deep learning-based image compression algorithms in this field. Implicit Neural Representation (INR) for image compression is an emerging technology that offers two key benefits compared to cutting-edge autoencoder models: low computational complexity and parameter-free decoding. It also outperforms many traditional and early neural compression methods in terms of quality. In this study, we introduce a new Mixed AutoRegressive Model (MARM) to significantly reduce the decoding time for the current INR codec, along with a new synthesis network to enhance reconstruction quality. MARM includes our proposed AutoRegressive Upsampler (ARU) blocks, which are highly computationally efficient, and ARM from previous work to balance decoding time and reconstruction quality. We also propose enhancing ARU's performance using a checkerboard two-stage decoding strategy. Moreover, the ratio of different modules can be adjusted to maintain a balance between quality and speed. Comprehensive experiments demonstrate that our method significantly improves computational efficiency while preserving image quality. With different parameter settings, our method can achieve over a magnitude acceleration in decoding time without industrial level optimization or achieve state-of-the-art reconstruction quality compared with other INR codecs. To the best of our knowledge, our method is the first INR-based codec comparable with Ballé et al. [1] in both decoding speed and quality while maintaining low complexity.
Jiahong Chen, Bin Chen 0011, Zimo Liu, Baoyi An 0002, Shutao Xia, Zhi Wang 0001
IEEE Trans. Multim.4
2024 Controller-Guided Partial Label Consistency Regularization with Unlabeled Data
abstract
Partial label learning (PLL) learns from training examples each associated with multiple candidate labels, among which only one is valid. In recent years, benefiting from the strong capability of dealing with ambiguous supervision and the impetus of modern data augmentation methods, consistency regularization-based PLL methods have achieved a series of successes and become mainstream. However, as the partial annotation becomes insufficient, their performances drop significantly. In this paper, we leverage easily accessible unlabeled examples to facilitate the partial label consistency regularization. In addition to a partial supervised loss, our method performs a controller-guided consistency regularization at both the label-level and representation-level with the help of unlabeled data. To minimize the disadvantages of insufficient capabilities of the initial supervised model, we use the controller to estimate the confidence of each current prediction to guide the subsequent consistency regularization. Furthermore, we dynamically adjust the confidence thresholds so that the number of samples of each class participating in consistency regularization remains roughly equal to alleviate the problem of class-imbalance. Experiments show that our method achieves satisfactory performances in more practical situations, and its modules can be applied to existing PLL methods to enhance their capabilities.
Qian-Wei Wang, Bowen Zhao 0003, Mingyan Zhu 0001, Zimo Liu, Shutao Xia
AAAI5
2024 Clip-Based Synergistic Knowledge Transfer for text-based Person Retrieval
abstract
Text-based Person Retrieval (TPR) aims to retrieve the target person images given a textual query. The primary challenge lies in bridging the substantial gap between vision and language modalities, especially when dealing with limited large-scale datasets. In this paper, we introduce a CLIP-based Synergistic Knowledge Transfer (CSKT) approach for TPR. Specifically, to explore the CLIP’s knowledge on input side, we first propose a Bidirectional Prompts Transferring (BPT) module constructed by text-to-image and image-to-text bidirectional prompts and coupling projections. Secondly, Dual Adapters Transferring (DAT) is designed to transfer knowledge on output side of Multi-Head Self-Attention (MHA) in vision and language. This synergistic two-way collaborative mechanism promotes the early-stage feature fusion and efficiently exploits the existing knowledge of CLIP. CSKT outperforms the state-of-the-art approaches across three benchmark datasets when the training parameters merely account for 7.4% of the entire model, demonstrating its remarkable efficiency, effectiveness and generalization.
Yaowei Li 0001, Zimo Liu, Wenming Yang, Yaowei Wang 0001, Qingmin Liao
ICASSP3
2024 CoTuning: A Large-Small Model Collaborating Distillation Framework for Better Model Generalization
abstract
Model compression and distillation techniques have become essential for deploying deep learning models efficiently. However, existing methods often encounter challenges related to model generalization and scalability for harnessing the expertise of pre-trained large models. This paper introduces CoTuning, a novel framework designed to enhance the generalization ability of neural networks by leveraging collaborative learning between large and small models. CoTuning overcomes the limitations of traditional compression and distillation techniques by introducing strategies for knowledge exchange and simultaneous optimization. Our framework comprises an adapter-based co-tuning mechanism between cloud and edge models, a scale-shift projection for feature alignment, and a novel collaborative knowledge distillation mechanism for domain-agnostic tasks. Extensive experiments conducted on various benchmark datasets demonstrate the effectiveness of CoTuning in improving model generalization while maintaining computational efficiency and scalability. The proposed framework exhibits a significant advancement in model compression and distillation, with broad implications for research in the collaborative evolution of large-small models.
Zimo Liu, Kangjun Liu, Mingyue Guo 0001, Shiliang Zhang, Yaowei Wang 0001
ACM Multimedia1
2024 M$^3$GPT: An Advanced Multimodal, Multitask Framework for Motion Comprehension and Generation
abstract
This paper presents M$^3$GPT, an advanced $\textbf{M}$ultimodal, $\textbf{M}$ultitask framework for $\textbf{M}$otion comprehension and generation. M$^3$GPT operates on three fundamental principles. The first focuses on creating a unified representation space for various motion-relevant modalities. We employ discrete vector quantization for multimodal conditional signals, such as text, music and motion/dance, enabling seamless integration into a large language model (LLM) with a single vocabulary. The second involves modeling motion generation directly in the raw motion space. This strategy circumvents the information loss associated with a discrete tokenizer, resulting in more detailed and comprehensive motion generation. Third, M$^3$GPT learns to model the connections and synergies among various motion-relevant tasks. Text, the most familiar and well-understood modality for LLMs, is utilized as a bridge to establish connections between different motion tasks, facilitating mutual reinforcement. To our knowledge, M$^3$GPT is the first model capable of comprehending and generating motions based on multiple signals. Extensive experiments highlight M$^3$GPT's superior performance across various motion-relevant tasks and its powerful zero-shot generalization capabilities for extremely challenging tasks. Project page: \url{https://github.com/luomingshuang/M3GPT}.
Mingshuang Luo, Ruibing Hou, Hong Chang 0001, Zimo Liu, Shiguang Shan
NeurIPS5
2023 Lifelong Person Re-identification via Knowledge Refreshing and Consolidation
abstract
Lifelong person re-identification (LReID) is in significant demand for real-world development as a large amount of ReID data is captured from diverse locations over time and cannot be accessed at once inherently. However, a key challenge for LReID is how to incrementally preserve old knowledge and gradually add new capabilities to the system. Unlike most existing LReID methods, which mainly focus on dealing with catastrophic forgetting, our focus is on a more challenging problem, which is, not only trying to reduce the forgetting on old tasks but also aiming to improve the model performance on both new and old tasks during the lifelong learning process. Inspired by the biological process of human cognition where the somatosensory neocortex and the hippocampus work together in memory consolidation, we formulated a model called Knowledge Refreshing and Consolidation (KRC) that achieves both positive forward and backward transfer. More specifically, a knowledge refreshing scheme is incorporated with the knowledge rehearsal mechanism to enable bi-directional knowledge transfer by introducing a dynamic memory model and an adaptive working model. Moreover, a knowledge consolidation scheme operating on the dual space further improves model stability over the long-term. Extensive evaluations show KRC’s superiority over the state-of-the-art LReID methods with challenging pedestrian benchmarks. Code is available at https://github.com/cly234/LReID-KRKC.
Chunlin Yu, Ye Shi 0001, Zimo Liu, Shenghua Gao, Jingya Wang 0001
AAAI3
2020 Pose-Guided Visible Part Matching for Occluded Person ReID
abstract
Occluded person re-identification is a challenging task as the appearance varies substantially with various obstacles, especially in the crowd scenario. To address this issue, we propose a Pose-guided Visible Part Matching (PVPM) method that jointly learns the discriminative features with pose-guided attention and self-mines the part visibility in an end-to-end framework. Specifically, the proposed PVPM includes two key components: 1) pose-guided attention (PGA) method for part feature pooling that exploits more discriminative local features; 2) pose-guided visibility predictor (PVP) that estimates whether a part suffers the occlusion or not. As there are no ground truth training annotations for the occluded part, we turn to utilize the characteristic of part correspondence in positive pairs and self-mining the correspondence scores via graph matching. The generated correspondence scores are then utilized as pseudo-labels for visibility predictor (PVP). Experimental results on three reported occluded benchmarks show that the proposed method achieves competitive performance to state-of-the-art methods. The source codes are available at https://github.com/hh23333/PVPM.
Shang Gao 0012, Jingya Wang 0001, Huchuan Lu, Zimo Liu
CVPR4
2019 Deep Reinforcement Active Learning for Human-in-the-Loop Person Re-Identification
abstract
Most existing person re-identification(Re-ID) approaches achieve superior results based on the assumption that a large amount of pre-labelled data is usually available and can be put into training phrase all at once. However, this assumption is not applicable to most real-world deployment of the Re-ID task. In this work, we propose an alternative reinforcement learning based human-in-the-loop model which releases the restriction of pre-labelling and keeps model upgrading with progressively collected data. The goal is to minimize human annotation efforts while maximizing Re-ID performance. It works in an iteratively updating framework by refining the RL policy and CNN parameters alternately. In particular, we formulate a Deep Reinforcement Active Learning (DRAL) method to guide an agent (a model in a reinforcement learning process) in selecting training samples on-the-fly by a human user/annotator. The reinforcement learning reward is the uncertainty value of each human selected sample. A binary feedback (positive or negative) labelled by the human annotator is used to select the samples of which are used to fine-tune a pre-trained CNN Re-ID model. Extensive experiments demonstrate the superiority of our DRAL method for deep reinforcement learning based human-in-the-loop person Re-ID when compared to existing unsupervised and transfer learning models as well as active learning models.
Zimo Liu, Jingya Wang 0001, Shaogang Gong, Dacheng Tao, Huchuan Lu
ICCV1
2019 Person Reidentification by Joint Local Distance Metric and Feature Transformation
abstract
Person reidentification is of great importance in visual surveillance and multiperson tracking across multiple camera views. Two fundamental problems are critical for person reidentification: 1) how to account for appearance variation or feature transformation caused by viewpoint changes and 2) how to learn a discriminative distance metric for reidentification. In this paper, we propose an algorithm in which both feature transformation and metric learning are exploited and jointly optimized. We learn local models from subsets of training samples with regularization imposed by the global model which is trained among the entire data set. The learned local models enhance the discriminative strength and generalization ability. Experimental results on the Viewpoint Invariant PEdestrian Eecognition, Queen Mary University of London ground reidentification, CUHK01, and CUHK03 benchmark data sets show that the proposed sample-specific view-invariant approach performs favorably against the state-of-the-art person reidentification methods.
Zimo Liu, Huchuan Lu, Xiang Ruan, Ming-Hsuan Yang 0001
IEEE Trans. Neural Networks Learn. Syst.1
2017 Stepwise Metric Promotion for Unsupervised Video Person Re-identification
abstract
The intensive annotation cost and the rich but unlabeled data contained in videos motivate us to propose an unsupervised video-based person re-identification (re-ID) method. We start from two assumptions: 1) different video tracklets typically contain different persons, given that the tracklets are taken at distinct places or with long intervals; 2) within each tracklet, the frames are mostly of the same person. Based on these assumptions, this paper propose a stepwise metric promotion approach to estimate the identities of training tracklets, which iterates between cross-camera tracklet association and feature learning. Specifically, We use each training tracklet as a query, and perform retrieval in the cross-camera training set. Our method is built on reciprocal nearest neighbor search and can eliminate the hard negative label matches, i.e., the cross-camera nearest neighbors of the false matches in the initial rank list. The tracklet that passes the reciprocal nearest neighbor check is considered to have the same ID with the query. Experimental results on the PRID 2011, ILIDS-VID, and MARS datasets show that the proposed method achieves very competitive re-ID accuracy compared with its supervised counterparts.
Zimo Liu, Dong Wang 0004, Huchuan Lu
ICCV1